3.3 engine misfires

[garceau83]

Help. I have a 1990 Plymouth voyager with the 3.3 engine that ran perfect until last week. It has 90K miles. Was driving at about 15 MPH and stepped on the gas a little and got a big backfire. It did it once again when I stepped on the gas.

I made it home with out any problem. I then noticed it would back fire everytime I took off. It was getting worst by the minute.

I replaced the plugs and wires and it didn't help. Backfiring and missing got worst. Would idle a little rough but had deep explosions when taking off under load. (In gear with foot on brake)

Replaced the fuel filter. still the same thing. Pulled both valve covers and checked for broken rocker arm towers or broken springs. they were ok.
Did compression test. They were 140 -150 PSI. The number one plug was black as if it had been used for years. The other five were like new. Nice and shinny. I believe the #1 cylinder is the one that is doing the missing and backfiring. I have asked just about everyone and they don't have a clue. Could the engine controller cause this. the only code i get is 55.

I can do the wokrk, just tell me what to do.

Thanks to everyone who reads this post and considers a fix.

[jeff compton]

Switch the injector for cyl #5 with cyl #3 and redrive it for a while, see what
it does to that plug after a day or too. Just be sure to replace the o-rings or you'll only create more problems, clean engine oil helps the injectors go in easier

good luck and keep me postted

jeff